A series of three winter storms swept across the Pacific Northwest during the December 14-22, 2008 time period producing significant snowfall amounts across the region. An arctic air mass moved into the region on December 14 and persisted through Dec 22. During this period, valley temperatures in the teens to mid 20s were common.
On December 14th, a surface low pressure system slid down the Oregon and Washington coastlines, allowing an arctic airmass to build in the Columbia basin. Arctic air surged through the Columbia River Gorge, and over the Cascade mountains, filling the Willamette Valley and even plunging the coast into sub-freezing air. This would mark the beginning of a cold, and very snowy period that would last through Christmas Day for much of northwest Oregon and southwest Washington.
Snow began falling across much of northwest Oregon and southwest Washington as early as Wednesday, December 17th and continued at a relatively light rate through midday Saturday, December 20th. Accumulations from this period of snow were on the light side, generally from a Trace to a couple of inches for elevations below 500 ft.
On Saturday the 20th, another system moved southeast out of the Gulf of Alaska and spread periods of more intense precipitation across the forecast area from the afternoon of the 20th, through the day on December 22nd. This system would also cause bitterly cold east winds to spread over much of the greater Portland metro area. Snowfall accumulations from this part brought 12 to 20 inches of snow around the metro area. Local accumulations in the West Hills, and in the bluffs around Oregon City amounted to 25 to 30 inches. Also, ice was a problem in this storm.
It should be noted that, while portions of the Central and South Willamette Valley did see snow and ice accumulations during the beginning of this event, the prolonged cold weather, and significant snow accumulations were mostly confined to areas north of Salem.
For Notable Snowfall Amounts: Click on Public Information Statements below.